Quantifying health utilities of young adult orthodontic patients using the time trade-off method: a cross-sectional study

ABSTRACT Objective: To study the feasibility of time trade-off (TTO) method in quantifying health utility ratings in different types of malocclusion. Material and Methods: In this cross-sectional study, 70 orthodontic patients aged 18 years or above, reporting for treatment/consultation, were included and interviewed. Malocclusion-related health utilities were assessed through the TTO method, and oral health-related quality of life was measured with the help of Orthognathic Quality of Life Questionnaire (OQLQ). Angle’s classification of malocclusion was recorded. Bivariate analyses and multivariate Poisson’s regression were done to find out an association between the oral health utility values, OQLQ and demographic and clinical characteristics. Results: Patients with skeletal Class III malocclusion had lower health utility values than those with Class I and Class II malocclusions (p=0.013). Poisson’s regression showed that Angle’s Class II division 1 (0.90, CI 0.84 to 0.97), Class III (0.68, CI 0.59 to 0.95) and Skeletal malocclusion (0.79, CI 0.71 to 0.87) and OQLQ scores (1.0, CI 1 to 1.003) were found to be significant predictors of TTO utility scores. Conclusions: TTO utilities were found to be valid and well correlated with clinical findings. Health utilities could serve as useful and reliable markers of health-related quality of life (HRQL) among individuals or communities and help cost-effective preventive or intervention programs planning.

Conclusões: Os escores do TTO foram considerados válidos e bem correlacionados com os achados clínicos, e podem servir como marcadores úteis e confiáveis da qualidade de vida relacionada à saúde (health-related quality of life, HRQL) entre indivíduos ou comunidades, e ajudar no planejamento de programas de prevenção ou de intervenção, com uma boa relação custo-benefício. is willing to exchange in order to avoid living in a less than perfect health state. The underlying assumptions of the TTO method is that an individual with lower utility values has poorer health-related quality of life, and assigns a lower value (utility) to his current health status than someone with a higher TTO value.

Palavras
Malocclusion is often described as a morphological variation in which teeth are present in a deviant position in relation to adjacent teeth and/or the opposing teeth upon closure of the jaws. In India, the prevalence of malocclusion ranges from 20% to 92%. 4,5 Malocclusion has long-lasting ramifications on the psyche of an individual, and can have a negative effect on one's self image, career progress, societal acceptance and quality of life. They can also be associated with impaired masticatory function and speech. 1,6 In dentistry, specific HRQL questionnaires include the Psychosocial Impact of Dental Aesthetics Questionnaire (PIDAQ), 1 Oral Health Impact Profile (OHIP), 7 and the Orthognathic Quality of Life Questionnaire (OQLQ). 8 The OQLQ is the only instrument that explores the subjective influence of orthodontic specific conditions in young adults. 9 Most of the studies on malocclusion are focused on children/adolescents, as they are the key focus of orthodontics. In developing countries, however, orthodontics is still out of reach of vast sections of the population. Regular dental screening programs at schools or elsewhere are largely non-existent. The prohibitive cost of orthodontic treatment also plays a role in children neglecting orthodontic treatment at the adolescent stage.
A combination of self-awareness, peer pressure and relative financial independence make them seek orthodontic treatment in their early adult years. It has been reported that adults are more affected by their malocclusion, with significantly higher emotional and social impacts than adolescents. 10 A literature search revealed only one study where an attempt was made to measure utilities among orthodontic patients awaiting surgery to correct dentofacial deformities. 11 Studies that measured utilities among patients with different types of malocclusion were not reported in the literature. Hence, the objectives of the present study were to assess the feasibility of time trade-off (TTO) method in quantifying health utility ratings in different types of malocclusion. It was hypothesized that the TTO method would be effective in quantifying health utility ratings in different types of malocclusion.

MATERIAL AND METHODS
The STROBE guidelines were followed for describing the materials and methods. The study followed a cross-sectional design and was conducted for a duration of four months, from In addition, the OQLQ was administered and finally the TTO utility valuation was recorded. A pilot study was conducted considering data from twenty patients. The TTO value and OQLQ scores were used to calculate the Pearson's correlation coefficient (r = +0.38) of the pilot study sample, and the Fisher's arctan transformation was derived to account for the skewness of data. Taking α = 0.05 and β = 0.80, the minimum sample size calculated was sixty-eight, with an additional 10% for non-response, giving the total sample to 75.

TIME TRADE-OFF UTILITIES
TTO was measured through a qualitative interview in which the patients were asked to consider a hypothetical scenario.
The patients were told that a new treatment regimen existed that would permanently rectify the malocclusion (if any) they were suffering from. The treatment would always be successful; however, it would decrease their survival. The subjects were offered a Choice A, which was their full life span of 68 years, or Choice B, which had a lower life span but perfect oral health.       Poisson regression analyses was performed for TTO scores as dependent variable, and is shown in Table 4. The type of malocclusion and OQLQ scores significantly predicted TTO utility scores. Among types of malocclusion, specifically Angle's Class II division 1, Class III and Skeletal malocclusion were found to be significant predictors of TTO utility scores.